Methods for measuring the sagittal resistive torque of ankle-foot orthoses during gait: A systematic review

The measurement of resistive torque exerted by passive ankle-foot orthoses during walking plays a critical role in understanding their biomechanical effects and in optimizing their functionality. This systematic review investigates existing measurement methods to evaluate how orthotic torque is quantified during gait, offering insights into currently used methods and technologies. Because many methods are closely linked to the use of test benches, these methods are also discussed but are not the scope of this work. A comprehensive systematic search was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, encompassing databases such as PubMed, Scopus, Web of Science, and IEEE Xplore, and AI-assisted literature search tools. The selected keywords focus on passive ankle-foot orthoses, in-gait measurement, and torque-related outcomes. From an initial pool of 2237 articles, a systematic exclusion refined the selection to 30 relevant studies. These were categorized into 3 groups: indirect measurement methods using gait analysis, indirect measurement methods using instrumented orthoses, and direct measurement methods. The results highlight a lack of standardized methods for quantifying orthotic torque and for quantifying the properties of ankle-foot orthoses themselves. Many studies fail to detail their measurement techniques thoroughly. Although indirect methods dominate, they may lack measurement accuracy. Direct measurement methods appear to be more accurate but exhibit individual limitations. This review emphasizes the necessity for reliable measurement techniques to advance clinical practices and research. Addressing these gaps has the potential to enhance the design, functionality, and prescription of ankle-foot orthoses for improved patient care.